Tension device for sewing-machines



(No Model.)

G. R. PHARE. TENSION DEVICE FOR SEWING MACHINES..

No. 416,233. Patented Deo. 3 1889.

UNITED STATES PATENT OFFICE.

GEORGE R. PEARE, OF LYNN, ASSIGN OR OF ONE-.HALF TO EDWIN L.

SPRAGUE, OF BOST ON, MASSACHUSETTS.

TENSION DEVICE FOR SEWING-MACHINES.

SPECIFICATION forming part of Letters Patent N o. 416,233, dated December 3, 1889.

Original application filed April 24, 1888,

To ctZZwz/om it may concern:

Beit known that I, GEORGE R. PEARE, of Lynn, county of Essex, State of Massachusetts, have invented an Improvement in Sewing-Machines, of which the following descrip-- tion, in connection with the accompanying drawings, is a specification, like letters on the drawings representing like parts.

This invention has for its object to improve the tension mechanism employed in wax-thread sewing-machines having a horn, so that the thread taken bythe usual hooked needle from the usual whirl supported in the tip of the horn maybe -subjected toa uniform tension.

In my invention the thread is subjected between a rotating thread-holder and the Whirl in the tip of the horn to the action of a lever, the effective strain of which upon the thread is made adjustable according to the thread being used and the work being done, the said lever through a spring exerting more or less friction tothereby establish the desired degree of tension for the thread, the force of the spring upon the lever and the friction exerted on the thread-holder being overcome by the force of the pull of the thread on the lever, the force exerted by the thread to move the lever being always less than the strain or force required to be put on the thread to turn the thread-holder.

Figure l shows a sufcient portion of the horn of a sewing-machine with my improvements added to enable my invention to be understood, and Fig. 2 a detail in elevation of the thread-holder.

The rotating horn A2 is and may be of any usual construction, and at its tip it will contain a whirl w, through a hole in which is eX- tended the thread c, which is to be presented to the usual hooked needle, all as in the McKay sewing-machine, the said needle not being herein shown because well known and not of my invention. The horn or an arm thereof has pivot-ed upon it at ct a lever b, herein shown as provided at its outer end with the roll or sheave b to lessen the wear of the lever on the thread c. (Shown by dotted lines.) The horn has rising from it a rod d,

which is extended up through a thread-holder -holder about which Serial No. 271,667. Divided and this application led December 18, 1888. Serial No.

(No model.)

horn, while a nut, as cl2, on the rod d, acting" through a spring, as e, is made to eXerta certain friction or pressure which is thrown upon the thread-holder to measure the thread-tension. The spring e measures the degree of friction to which the sleeve or spool of the threadthe thread is wound is subjected.

I do not desire to limit my invention to the particular form of spring shown.

The operator will adjust the force of the spring e according to the strength of' the thread and the work to be done, and the spring will be so set that the resistance offered by it to the movement of the lever b is always less than the resistance which is to be overcome by the thread to turn the .threadholder. In this manner it will be seen that the tension upon the thread may be maintained substantially uniform in extent.

In wax-thread sewing-machines using a horn the thread is at times taken directly from a large spool and at other times taken froin a'waXing-cup and carried about a rotating sleeve or spool.

In my invention the thread may be wound, as represented by dotted lines 4, directly upon the thread-holder, shaped like a sleeve or spool, or the thread-holder may have its lower head or end grooved, as represented at l0, to enable the thread coming from a wax-l cup or other thread-supply (not shown) to be.

wound once around the said end or head, and whichever plan is adopted it will be noticed that the sleeve or spool will be held against rotation by a friction measured by the spring e referred to co-operating with the lever T).

The shape of the lever b may be variously modiiied without departing from my invention.

I do not broadly claim the employment of the lstrain on the thread to separate two tension-plates and effect the tension on the thread passing between them.

I claim- In a wax-thread sewing-machine, the combination, with the horn and the rotating thread- IOO holder and its supporting-rod, of the lever b, In testimony Whereofhave signe my name pivoted att one end upon the horn and carryto this specification in the presence of two ing a sheave or 11011 at its other end and restsubscribing Witnesses. in g upon the thread-holder between these two GEO. R. PEARE.

ends, a nut on the rod over the lever, and a Witnesses: spring interposed between the lever `and nut, G. W. GREGORY, substantially as set forth. M. RAY. 

